#include <fstream>
using namespace std;

ifstream f("holiday.in");
ofstream g("holiday.out");

int a,b,x;
int ans;

int main()
{
    int i;

    f>>a>>b>>x;
    ans=1;

    for(i=x;i>=2;--i)
    {
        if(x%i==0)
        {
            if((b-a)%i==0) if(ans==1) {ans=i;break;}
        }
    }

    g<<ans<<"\n";

    f.close();
    g.close();
    return 0;
}